(16) Psyche is the largest known M-class asteroid (240 x 185 x 145 km), and a density of 5 – 8 g/cm(3) is inferred from orbit perturbations of nearby asteroids. Other ground observations suggest that the surface and dust around this object is iron-nickel rich with very little water. These observations are important considering the… Read more »

An important aspect of community-wide efforts to understand the geologic and climatic history of early Mars is to constrain the style(s) and timing of resurfacing events in the Noachian. The cratered plains of the ancient highlands exhibit diversity in compositional and thermophysical properties, providing some constraints on the resurfacing history and thus the processes and… Read more »

Low material transmission and reflection in the far-ultraviolet has posed a major constraint on astronomy in the observed-frame UV. The most prominent NASA observatory with sensitivity in the Lyman ultraviolet, FUSE, had limited angular resolution and high background equivalent flux introduced by the need to minimize reflections to maintain effective area. The spectroscopic imaging capabilities… Read more »

When NASA’s New Horizons spacecraft flew past Pluto and its five moons last July, it revealed a beautiful, varied, and puzzling system. Pluto’s surface ranges from dark and cratered terrains, to tall mountain ranges, to geologically young ice flows. Charon sports a completely unexpected dark, reddish area near its north pole. Pluto’s atmosphere is hazy… Read more »

The early bombardment of the inner solar system played a critical role in planetary evolution, but there is still considerable uncertainty about what happened when. Dynamical models suggest two major bombardment phases may have taken place: (i) a post-accretionary period where newly-formed worlds were struck by leftover planetesimals, and (ii) a late heavy bombardment period,… Read more »

After traveling for more than 9 years, NASA’s New Horizons mission accomplished its prime objective – the initial reconnaissance of the Pluto system. On July 14, New Horizons passed about 12,500 km from Pluto’s surface, flying between Pluto and the orbit of Pluto’s large moon Charon. The seven instruments on board the spacecraft include a… Read more »

Solar flares are the result of magnetic reconnection in the solar corona which converts magnetic energy into kinetic energy resulting in the rapid heating of solar plasma. Characterizing how this hot plasma subsequently cools is important for understanding the evolution of flares and the corresponding heating of the quiescent corona. Because the flare soft x-ray… Read more »

The 21st of May 2010 saw the dawn of a new era in space propulsion when the Japanese Space Agency, JAXA, launched its IKAROS spacecraft. Twenty days into the mission, IKAROS unfurled a 14×14 m2 solar sail that would take the probe on a six-month voyage to Venus, propelled solely by the solar photons reflecting… Read more »

What if Jack Eddy hadn’t rediscovered the work by Gustav Spörer and Edward W. Maunder about the period of few sunspots in the 17th century? Would there be much interest today in understanding the solar “constant”, or would there be robust observational programs in measuring the solar irradiance and its variability and studies about Sun-Climate?… Read more »

Precise photometry from the Kepler space telescope allows not only the measurement of rotation in solar-type field stars, but also the determination of reliable masses and ages from asteroseismology. These critical data have recently provided the first opportunity to calibrate rotation-age relations for stars older than the Sun. The evolutionary picture that emerges is surprising:… Read more »

Sudden stratospheric warmings (SSWs) are first-order dynamical events in the polar winter stratosphere, which are known to influence tropospheric variability on medium range time scales of roughly 10-60 days. Here we present results from the development of a SSW compendium composed of processed data derived from six modern reanalysis products. The aim of this compendium… Read more »

Some of the most fundamental and complex problems in climate and weather research today are our poor understanding of the basic properties of clouds and our inability to determine quantitatively the many effects that clouds have on weather and climate. The representation of ice microphysical processes such as riming, sedimentation, aggregation, evaporation and deposition has… Read more »

Thirty years ago, the 12th of March 1986, the European Giotto spacecraft flew by Comet Halley, obtaining the conclusive evidence that comets indeed have a nucleus. The series of images obtained by the Halley Multicolour Camera was abruptly interrupted when a cometary dust grain blew away its external structure (plane mirror and baffle), thus preventing… Read more »

In July 2015, the New Horizons mission gave us our first detailed view of the Pluto system after a 9.5 year journey from Earth. New Horizons revealed that Pluto’s geology is complex and remarkably diverse. Ancient cratered and fractured terrain is interrupted by much younger features that are likely active to the present day, including… Read more »

The Imaging Ultraviolet Spectrograph (IUVS) is one of nine science instruments aboard the Mars Atmosphere and Volatile and EvolutioN (MAVEN) spacecraft, whose payload is dedicated to exploring the upper atmosphere of Mars and understanding the magnitude and drivers of Mars’ atmospheric escape rate. IUVS uses ultraviolet light to investigate the lower and upper atmosphere and… Read more »

NASA’s New Horizons mission to the Pluto-Charon system has returned a wealth of data about these objects currently 33 AU from the sun. Among those data are information about impact craters on four of these bodies. Impact craters offer a glimpse into many exogenic and endogenic processes that have informed and are informing the science… Read more »

Instead of starting with an unstable electron beam, the excitation of Langmuir waves is considered in the stable two-electron plasma after beam stabilization in which the velocity distribution function of the second population forms a plateau (p) with a more or less extended region of ¶fp/¶v=0. As shown by PIC simulations, this so-called plateau plasma… Read more »

This talk will discuss the light scattering properties of different species of micron-scale dust particles and how to quantify their chemical composition and physical properties (e.g., size, shape, packing density or porosity of collections of grains) through a combination of radiative transfer modeling and laboratory analog spectroscopy at UV to IR wavelengths. The value of… Read more »

Magnetic fields can seem like magic. Indeed, the earliest uses of naturally-magnetic lodestones were for fortune telling, and to this day magnetism is a popular source of power for comic-book superheroes and supervillains alike. The reality of magnetism is, if anything, more compelling. It can affect the dynamics of stars and galaxies, but also how we live our daily lives. From the first use of… Read more »

Not long after its closest encounter with Pluto last July, the Alice ultraviolet imaging spectrometer onboard New Horizons successfully observed spectral signatures of UV absorption by Pluto’s atmosphere during a solar occultation event. During this event, a UV bright star (more specifically, the Sun) passed behind Pluto as seen by the spacecraft, and the attenuated… Read more »